1. Field of the Invention
The present invention is directed to processes for the preparation of optically-active (mixed) anhydrides and acids.
2. Description of the Prior Art
Carboxylic acids are of interest because they or their esters, salts and the like often have useful effects in biological systems, e.g. as herbicides, plant growth regulators, analgesics, antipyretics, antiinflammatory agents, or also in the form of esters as insecticides and miticides. In particular, the optically-active acids and their esters, salts and the like usually have some different effects in biological systems from those of their enantiomers. Although a variety of methods to obtain optically-active acids are known, these acids are usually obtained by classical resolution, which is time consuming and not practical on a large scale.
The present process provides a process for preparing optically-active acids or (mixed) anhydrides in high yield by a direct synthesis method, avoiding the cumbersome and expensive classical resolution of the optically-active acids.